Driving gear frame encased in shell section housing



K. PFAFF April 10, 1956 DRIVING GEAR FRAME ENCASED IN SHELL SECTIONHOUSING Filed May 17, 1952 United States Patent O DRIVING GEAR FRAMENCASED IN SHELL SECTIN HOUSING Karl Pfat, Kaiserslautern, Germany,assigner to G. M. Pfa A.G., Kaiserslautern, Germany Application llay 17,1952, Serial No. 288,43

3 Claims. (Cl. 1212-258) The invention relates to a sewing machinehaving a driving gear frame which is enclosed by shell sections. Theshell sections which constitute the housing may be made of steel plate,die castings, plastic or other suitable moldable materials.

ln household sewing machines with electric drive the motor with thestarter and components has been accommodated, for example, in a housing,the shells of which have been made in two parts permitting observationof the electrical connection after removing the front half or thehousing. This housing was secured to the outside of the upper portion ofthe machine by means of a supporting arm.

It has also been proposed to enclose the motor and its component partsin the enclosure of the driving gear frame by disposing the electricalparts sidewise of the driving gear frame and by forming the enclosure asa laterally projecting, removable shell.

On the other hand, it has also been proposed to construct the upperportion of the sewing machine in the manner of a chassis and to encloseit by means of shells of metal plate, plastic or the like. In the knownembodiments of this type, however, the chassis did not carry allnecessary components for the operation of the sewing machine. Thebalance wheel was disposed outside the shells and also the illuminationarrangement was not conlined within the shells enclosing the chassis.The power transmission means were likewise outside the shell portionswhich formed the housing of the sewing machine.

It is the purpose of the invention to undertake the encasing of themachine components including the driving gear frame in such a mannerthat the shell parts form a unitary structure which is closed withrespect to the outside thus imparting to the sewing machine anattractive appearance. The invention solves this problem particularly inthat the drive gear frame which is preferably constituted of a singlemember carries also the entire electrical fittings including motor,lighting device with connecting lead, socket to connect the supply line,socket to connect the starter and, as the case may be, transformer andswitch for the lighting device, and that the entire installation isenclosed by shells in such a manner that a unitary structure is formedwhich is closed to the outside and without having noticeably protrudingparts.

In accordance with the invention the upper and the lower parts of thedriving gear frame with all machine components carried thereby areenclosed by three shell portions in a manner that the entire upperportion of the driving gear frame including the standard is encompassedby two shell portions.

The outer shell portion of the upper part and of the standard portion ofthe driving gear frame can be provided with a segment shaped cut-out topermit a portion of the hand or balance wheel to protrude. Furthermore,this shell portion along the standard section may have an aperture forthe outwardly projecting lever on the elec- "ice trical motor which ispivotally supported on the driving gear frame, and movable by said leveragainst the force of a spring, and which transfers its torque to thebalance wheel. The lever is also provided with a catch. Finally, 'thisshell portion can also be provided with an aperture for inserting aspool which can be placed upon the end of the motor shaft which isformed as a spool carrier.

it is particularly advantageous that this construction permits the drivegear frame to be made as a single part. The production and particularlythe mounting can now be effected in a clearly visible manner because allof the components required for the sewing operations are secured to thedrive gear frame and are readily accessible and arranged in a manner topermit easy surveillance.

instead of providing'a socket for the connection of the starter it isalso possible to install the starter directly upon the driving gearframe. In that case it is also possible to provide a knee lever in thewell known manner by means of which the starter can be operated. Furtherfeatures of the invention and details of the advantages provided by itwill be apparent from the following description with reference to theappended drawings which schematically illustrates the embodiments of theshell enclosures for sewing machines in accordance with the invention.

Fig. l is a front view showing the driving gear frame and a crosssection through the shells along lines I-I of Fig. 2;

Fig. 2 is a cross section along line'II-II of Fig. l;

Fig. 3 is a cross section along line III-III of Fig. 1;

Fig. 4 illustrates to an enlarged scale a partial cross section alongline IV-IV of Fig. 2.

In the unitary drive gear frame the upper drive shaft 2 and the lowerdrive shaft 3 are supported in the well known manner. The connectionbetween the two drive shafts is by means of a chain belt 4 which restson gears S and 6. The upper drive shaft operates the needle shaft 9 andthe thread take up lever 10 by way of the crank plate 7 and theintermediate link 8. The shuttle drive means 11 is connected in theknown manner with the lower drive shaft 3. The hand or balance wheel 12is arranged upon the upper drive shaft 2. The friction disc 13 of themotor 14 applies rotary movement to the hand wheel 12 and drives themachine.

The motor 14 is likewise pivotally related to the driving gear frame bya joint 15. A pull spring 16 which is also fastened to the driving gearframe applies the pressure between the friction disc 13 of the motor andthe hand wheel 12 of the machine. The plug 17 for connecting thepowersupply is directly fastened to the drive gear frame, as well as thesocket 18 for connecting the adjustable starter switch, the sewing light19 and its connecting lead 20, the low voltage transformer 21, as wellas the push button switch 22 for the sewing light. The adjustablestarter proper may be secured to the drive gear frame instead of havingthe socket 18 for plugging in the starter. In that event supports mustbe provided for an insertable knee lever by means of which theadjustable starter is operated in the known manner. It is hereunderstood that the term adjustable starter switch refers to any motorcurrent limiting device conventionally associated with a sewing machinesuch as a rheostat switch arranged for progressive actuation by either ahuman knee acting on an appropriately positioned lever or through theagency of well known foot treadle means. Where such rheostat is locatedremote from power supply plug 17, it must, of course, be connected inthe circuit of motor 14 by some convenient means such as starter switchconnecting socket 1S.

The drive gear frame 1 with all driving parts of the sewing machine andthe components which form part of the electrical tittings in theconventional manner forms a chassis which is enclosed by shell sections23, 24 and 25. The shell sections may be made from metal plate, as diecastings, from plastics or similarmaterial. They impart an attractiveappearance to the sewing machine. In the outer shell section 23 a cutout indicated at 26 is'provided throughrwhich the hand wheel 12protrudes in the manner of a segment. vAll other parts of the chassisand of the electric ttings including the power transmission arrangementare inclosed by the sheils. A lever arm or catch bolt 27 having a bossor protuberancc 2S permits pivotally moving the motor against the forceof the spring 16 in a manner that the boss 28 interlocks with anaperture 28a in shell section 23. The resulting oblique displacement ofthe motor permits the placing of a bobbin through the opening 29 uponthe end Voli shaft 3 0 of the motor 14 which is in the orm of a bobbinshaft. In this manner it is also possible to prevent running of themachine while threading the bobbin. Upon removing the bobbin the motorcan again be placed in operative position under the eect of spring 16 byraising lever 27.

Having now described my invention what I claim as new and desire toprotect by Letters Patent is:

l. A sewing machine comprising a plurality of shells delining a housingand a unitary structure defining a driving gear frame supporting thedriving gear including the balance wheel and the electrical ttings andleads to operate a sewing light and a starter switch connecting socket,said driving gear frame being a substantially U- shaped configurationand having a horizontal base p0rtion, a vertical standard portion and anupper horizontal arm portion and said shells forming a housingconforming to the U-shaped configuration of the driving gear irme andenclosing the same and the aforesaid elements thereon, and a motor withits shaft substantially parallel to the vertical standard portion ofsaid frame and in driving engagement with the balance wheel, saidvertical standard portion and said motor being disposed in the portionof said housing enclosing the vertical standard portion, said motorhaving a lever arm projecting outside said housing and said motortbeingpivotally supported for movement by said lever arm to disengage saidbalance wheel, and said lever arm having a protuberance adapted tointerlock with said housing to maintain said motor disengaged from saidbalance wheel.

2. A sewing machine comprising a plurality of shells defining a housingand a unitary structure dening a driving gear frame supporting thedriving gear including the balance wheel and the electrical iittings andleads to operate a sewing light and a starter switch connecting socket,said driving gear frame being of substantially U-shaped configurationand having a horizontal base portion, a vertical standard portion and anupper hori- Cir its said driving engagement with Vsaid balance wheel,one` end of the shaft of said motor having a conformation adapted tosupporta bobbin and said `housing havingvan aperture and saidmshaftbeingin alignment with said v aperture to receive" a bobbin therethroughwhile said motor and said balance wheel aredisengaged. y v v 3. A sewingmachine having a driving gear frame in the form of a unitary structurelsupporting the complete mechanical driving gear including Vthe balancewheel and adapted to support the electrical equipment includinga motor,an electric light, connecting sockets, switcha starter switch connectingsocket, transformer and con,-

nectng leads, said driving gear frame being of substantially U-shapedconfiguration and having a horizontal base portion,'a vertical standardportion and anvupper horizontal arm portion, said machine including ahousing conforming to the U-shaped conguration of the driving gear frameand dei-ined by shells enclosing said frame and the components carriedthereby, the upper outer shell having a cut-out portion'disposed arounda protruding segment of the balance wheel and an aperture sidewisethereof, said motor being pivotally secured to the vertical standardportion of said frame with its shaft normally in a vertical positionparallel to the vertical standard frame portion, spring means secured tosaid driving gear frame and said motor and arranged to hold said motorin driving engagement with the balance wheel,

v said motor having a lever arm extending through a slot deiined in saidhousing and said lever arm having a protuberance adapted to engage anedge of said slot to hold said motor in an inclined position in axialalignment with said aperture.

References Cited in the `tile of this patent UNITED STATES PATENTS1,394,320 Mace Oct. 18, 1921 1,978,281 Pfat Oct. 23, 1934 2,430,932Hohmann Nov. 1S, 1947 2,704,527 Theenhausen Mar. 22, 1955 FOREIGNPATENTS 240,607 Switzerland Apr. 1, 1946

